It's a part of the Gas Jockey's Gear item set, which includes the Degreaser and the Powerjack. When the weapons and the hat are worn at the same time, the player gets the buffs and debuffs of the weapons as well as the following bonuses:
- +10% faster move speed on wearer
- +10% bullet damage vulnerability on wearer
The hat is craftable by combining 4x Refined Metal and either the Degreaser or the Powerjack.